Purpose: Different insertion angles of the rotary files during the root canal shaping may influence the cyclic fatigue resistance (CFR). The present study aimed to evaluate the effects of different insertion angles on a file’s static CFR at body temperature.
Methods: Eighty new Neoniti (Neolix, Châtres-la-Forêt, France) 25 mm long files were used. The stainless-steel metal block had four artificial canals with different insertion angles (0°, 10°, 20°, and 30°). The files were subjected to a static cyclic fatigue procedure at simulated body temperature (36 ± 1). The number of cycles to failure (NCF) and fractured instrument length were recorded. The Kruskal–Wallis H test analyzed the data at a 95% confidence interval (p = 0.05).
Results: For #20.06 and #25.06 instrument, the 10°, 20°, and 30° insertion angles resulted in decreased static fatigue resistance as compared to straight (0°) insertion angle (p< 0.05).
Conclusion: When the insertion angle increases, the static CFR decreases. An inclined insertion into the canals decreased the CFR of the endodontic instruments.